These vessels are the nitrogenous excretory organs.
The excretory organs, the 5.
The excretory tubes, the nervous system, and the parenchyma and integument are continuous from one end of the worm to the other.
A, Dorsal view showing the nervous system and digestive system; a, mouth; b, pharynx; c, d, e, gut; E, post-genital union of two limbs of gut; f, excretory pore; g, vaginal pore; h, j, k, brain and nerves; 1, dorsal nerves; m, ventral nerves; n, adoral sucker; o, posterior sucker; p, hooks on posterior sucker; r, vitello-intestinal duct.
2, D) and canaliculi of the excretory system as in Turbellaria, others again muscle-cells.